More than a quarter of the world population speaks tone languages. Among them, Mandarin Chinese is the most commonly spoken. In tone languages, the pitch or tone pattern of a monosyllabic word conveys lexical meaning. The paucity of pitch information for complex sounds (such as speech signals) in current cochlear implant design imposes a special challenge for patients who speak tone languages. The purpose of the proposed study is to investigate tone development (i.e., tone perception and tone production) in Mandarin speaking children with cochlear implants. Factors associated with tone development will be identified. Potential factors include chronological age, age of onset of deafness, duration of implant use, family background, speech-processing strategy used, educational characteristics, etc. In the proposed study, all subjects will be recruited from the patient population at Beijing Tongren Hospital, the largest cochlear implant center in China. Native Mandarin-speaking young children who have received multichannel cochlear implants (N= 60), age-matched normal-hearing children (N= 60), and hearing-impaired children (N =60) will be tested for their tone perception, the ability to recognize different tone patterns in Mandarin monosyllabic words. In addition, speech materials will be recorded from normal-hearing and cochlear-implant children. The speech samples will then be used for: 1) acoustic analysis of the tone patterns; and 2) perception tests in which normal-hearing native Mandarin-speaking adults (N= 10) will perform tone recognition on the syllables produced by the children and judge the intelligibility of the children's tone production. Multiple regression analyses will be performed to identify any associations of the above listed factors with the tone perception and production measures. Although the proposed study is primarily concerned with tone perception and production, it has important implications for speakers of non-tonal languages. A better representation of pitch information would be helpful in separating multiple talkers and providing music perception for cochlear-implant users. Therefore, the proposed study could improve quality of life for many cochlear implant users.